OGX slumped 9.3 percent to 1.17 reais in Sao Paolo yesterday. That helped erase $196 million from his net worth, and left the 56-year-old tycoon with a fortune of $6.1 billion, according to the Bloomberg Billionaires Index. His wealth peaked at $34.5 billion in March last year, when he was the eighth-richest person on Earth.

Batista sold 70.5 million shares between May 24 and May 29 for 121.8 million reais ($56.7 million), according to a regulatory filing. He had previously spent 2 billion reais since the 2008 initial public offering to buy shares.

“The market is now starting to ask why the controlling shareholder is selling his shares,” said Lucas Brendler, who helps manage about 4 billion reais at Geracao Futuro Corretora in Porto Alegre, Brazil. “The attitude is totally negative.”

Batista is selling assets that include his Embraer Legacy 600 jet to raise cash as his startups accumulate losses. Last month, he raised 1.4 billion reais by selling a stake in power-generation venture MPX Energia SA (MPXE3) to Germany’s EON SE. Separately, OGX sold an $850 million stake in an oil field to Malaysia’s Petroliam Nasional Bhd.

A spokeswoman for Batista’s holding company EBX Group Co., who asked not to be identified in accordance with corporate policy, declined to comment on Batista’s sale of OGX shares and the drop in his net worth.

Cash Warning

Excluding the options program that allows OGX management to buy shares from him as part of their compensation, it’s the first time Batista sold shares in his most valuable company since OGX’s 2008 IPO, data compiled by Bloomberg show.

“For him to sell at this level, he must really need the cash,” said Fabio Cardoso, a partner at Rio de Janeiro-based equity advisory firm Adinvest Consultoria, in a telephone interview. “It’s not a good sign.”

OGX may need to raise $1 billion from Batista through a put option to cover spending in 2014, Standard & Poor’s said in April after cutting the company’s credit rating. Under terms of the option, which expires May 2014, Batista would pay 6.3 reais per share, as much as four times the price he sold at last month.

Doubts Raised

Batista’s sale of OGX stock is a sign that the put option isn’t a sure thing, said Eric Conrads, who manages about $750 million of Latin American stocks at ING Investment Management in New York.

“Why would you sell at 1.5 reais if you have to buy at 6?” Conrads said by phone. “If you sell at those levels to buy the stock back four times higher, it doesn’t make a lot of sense.”

Five of Batista’s six trading units dropped yesterday as Brazil’s stock market entered a bear market amid faltering economic growth. OGX was the most traded by volume and the worst performer on Brazil’s benchmark Ibovespa index. While LLX Logistica SA (LLXL3), the tycoon’s port developer unit, lost 7.4 percent, the second-worst stock on the Ibovespa, his mining company MMX Mineracao & Metalicos SA fell 7.2 percent. The price on OGX’s bonds due in 2018 slid 8.70 cents to 49.04 cents on the dollar yesterday, also a record low.